1. Field of the Invention
The present invention relates to a semiconductor device including an interconnection structure formed between an internal circuit, which decides a specification of the semiconductor device, and power supply leads.
2. Description of the Background Art
Various methods have been used for manufacturing semiconductor devices of which functions are selected by changing interconnection patterns at final stages in manufacturing processes in accordance with specifications of the semiconductor devices. For example, FIG. 10 schematically shows a semiconductor device of a bonding option type in the prior art. FIGS. 11 and 12 schematically show a semiconductor device of a master slice type. Referring to FIGS. 10-12, an IC chip 6 is provided at its surface with bonding pads 1a and 1b corresponding to a Vcc supply lead 7 and a reference (GND) supply lead 8. The IC chip 6 is provided with an internal circuit 2 for deciding the internal state. The internal circuit 2 receives a signal of "H" or "L". The internal circuit 2 discriminates a level of the supplied signal, and generates a signal for changing the specification of the circuitry in the IC chip 6 in accordance with the supplied signal. Therefore, the internal circuit 2 is connected to either the Vcc supply lead 7 or the GND supply lead 8.
In the type shown in FIG. 10, the bonding pads 1a and 1b are connected to the internal circuit 2 through a dedicated power supply interconnection 5. Only the Vcc supply lead 7 is connected to the boding pad 1a through a bonding wire 9, or only the GND supply lead 8 is connected to the boding pad 1d through the bonding wire 9, whereby the signal supplied to the internal circuit 2 is decided. The type described above is referred to as the "bonding option type".
In FIGS. 11 and 12, both the Vcc supply lead 7 and the GND supply lead 8 are connected to the bonding pads 1a and 1b through the bonding wires 9, respectively. Only one of dedicated power supply interconnections 5a and 5b, which are connected to the bonding pads 1a and 1b, respectively, is connected to the internal circuit 2, whereby the level of the signal applied to the internal circuit 2 is decided. The type described above is referred to as the "master slice type". For the master slice type, patterning masks complying with the specifications are prepared for manufacturing the power supply interconnections in the manufacturing process of ICs, and thereby the interconnection pattern shown in FIG. 10 or 11 is formed.
However, in order to decide the specification of the IC chip, the bonding option type shown in FIG. 10 requires the lead 7 (or 8) which is not used as well as the corresponding bonding pad 1a (or 1b), which impedes the reduction of a size of the IC chip 6. Further, the power supply interconnection 5 connected to the unused bonding pad 1a (or 1b) also requires a certain area on the surface of the IC chip 6, which also impedes the reduction of the size of the IC chip 6.
The master slice type shown in FIGS. 11 and 12 requires a plurality of patterning masks having different interconnection patterns corresponding to the specifications, which is not preferable in view of the manufacturing process and manufacturing cost.